1. Field of the Invention
The present invention relates to a method for the fabrication of a composite structure for various building components.
2. Description of the Prior Art
The use of composite structures is known, as such since the combination of a shaped plate and concrete can be employed for building preferred composite structures, wherein a generally steel profile plate, serves as a component more resistant to tensile stresses, and concrete, on the other hand, which serves as a structural component primarily taking up compressive forces. These type of composite structures have been disclosed, e.g. in Patent publications FI 57295, GB 1 469 478, DE 24 13 645 and DE 26 04 998. The profile plate often serves as a mold for pouring the concrete mass thereon. The grip between the concrete and profile plate can be improved by means of various holes and knobs and recesses made in the profile plate. Tensile stresses can be taken up also by means of various additional steels. Patent publications U.S. Pat. No. 4,121,943 and U.S. Pat. No. 4,559,276 disclose a method for manufacturing steel-fiber concrete, wherein the tensile stresses of concrete are transferred to thin fibers mixed in the concrete. Also known is the injection of concrete by several different applications.
A drawback in the prior known manufacturing methods of composite structures is that they are restricted to substantially horizontal position, casting technique and one-sided loading. Another drawback is the use of generally just one type of concrete in various parts of a structure and the production of unnecessarily thick structures. This results in a structure having a relatively heavy dead weight and yet a relatively low strength. In many applications, it is necessary to use temporary molds and support stands on the construction site and those must be subsequently disassembled. The profile plate in itself is not sufficiently strong enough to serve as a casting mold under a fresh concrete mass without additional reinforcement.
Several composite structures require the use of conventional concrete reinforcements which increases costs. The conventional iron-bar reinforcement of concrete does not often work in an optimum fashion due to position and shape. Too much expensive steel is generally used in view of what is actually needed, since the steel is often not positioned exactly where the tensions are. In prior known composite structures, the freedom of designing the end product is also limited due to the working technique. Fixing of additional components to the structure is inconvenient.
As a result of the inconvenience of the prior known fabrication methods of composite structures, it is in many cases preferable to manufacture elements in a factory and carry them to the construction site to be erected. This, however, leads to the inconvenience of having to carry around heavy building elements that might be damaged during transport. Heavy-duty transport and lifting equipment cannot be brought to every construction site, thus incurring extra costs.